This invention relates to an improved fluid flow diverter valve, which is adapted especially for use in the cleaning of tubing of heat exchangers.
It has previously been suggested that heat exchanger tubing may be internally cleaned by mounting brush-basket assemblies on the ends of the tubes, and then by flowing fluid first in one direction and then the other to cause the brushes to traverse the length of the tubes and then return to their original position. See the above-identified U.S. Pat. No. 3,319,710.
It has also previously been suggested as in the above-identified U.S. Pat. No. 3,973,592 to utilize a four-way valve for purposes of reversing fluid flow within the tubes to cause the cleaning brushes to move in both directions within the tubes.
It is also known to provide a valve with a movable frusto-conical plug element or the like and wherein the outer wall of the plug element is normally seated in a frusto-conical seat, but wherein the said outer wall of the plug may be lifted from its seat and turned during valve actuation. See, for example, the above-identified U.S. Pat. No. 4,286,625.
The present inventor is also aware of a recently developed four-way diverter valve construction having a cylindrical housing wall and two pair of in-line ports for connection to a heat exchanger condenser or the like. Disposed within the interior of the valve housing is a longitudinal hollow tubular fluid flow diverter element mounted for rotation on a transverse axis coinciding with the center axis of the cylindrical wall. The tubular diverter element is provided with an inner generally diametrical baffle which forms separate but parallel fluid flow passages therein. Diametrically opposed longitudinally extending radial ribs are disposed on the outer wall of the tubular diverter element and directly in line with the edges of the inner baffle. The end closure plates for the valve are provided with a first stop device for engagement by the diverter element ribs for properly positioning the diverter element in a normal position parallel to the in-line ports. A second stop means is provided for rib engagement to properly position the diverter element in rotated position when the fluid flow downstream of the valve is to be reversed.
Although the end edges of the tubular diverter element and the baffle have been machined to closely conform in curvature with the inner curvature of the cylindrical valve wall, and very close tolerances have been maintained therebetween and with the positioning stops, problems have arisen with the known valve.
When the tubular diverter element is in its normal position, fluid flows through the valve housing in a straight line between the upstream and downstream ports, with one flow being reversed from the other. The baffle of the tubular diverter element is intended to separate the oppositely flowing fluid. However, there is a fluid pressure drop between the supply and return side of the valve, and leakage or bypassing of fluid from the supply side to the return side has been observed, especially at the contacting interfaces of compound curvature between the end edges of the tubular diverter baffle and the inside cylindrical valve wall. Some bypass has also been observed in connection with the first stop means. The bypassing of fluid from the supply to the return side of the valve is highly undesirable because it lowers the efficiency of operation of the device downstream of the valve. Bypassing when the tubular diverter element is in its rotated position has also been observed.
In addition, it has been observed that when the tubular diverter element is rotated between positions, the end edges of the element tend to bind on the inner surface of the cylindrical wall as the edges slide thereacross. Machining the parts to less close tolerances could alleviate this problem, but the above-described bypassing would be undesirably increased even more.
It is a task or object of the present invention to improve the features and operation of the above-described valve known to the inventor. It is a further task to substantially decrease the bypassing of fluid between the supply and return sides of the valve. It is yet another task to substantially reduce or eliminate the problem of binding of the tubular diverter element to the cylindrical housing wall during rotation of the diverter element between positions. It is a further task to accomplish all of the above tasks in an economical manner.
In accordance with the various aspects of the invention, diagonally opposed ports in the valve housing are surrounded by concave seats which are inclined at an acute angle to the cylindrical housing wall and the axis of rotation of the tubular diverter element. The end edges of the diverter element wall and baffle ends are slanted transversely at substantially the same angle to provide an engageable planular interface, in section, between the parts. Each seat extends circumferentially toward the other adjacent port and is intersected by a central longitudinal plane containing the baffle of the tubular diverter element when the element is in its normal position so that the seat terminates on the side of the diverter element baffle remote from the surrounded port when the diverter element is in normal position.
An axle mounts the tubular diverter element for rotation about its axis. A device is provided to shift the axle axially when desired. Thus, the diverter element and its associated parts can be tightened onto the seats, but also when the diverter element is to be rotated from its normal to its second position, the end edges of the associated parts can be lifted from the circumferential tapered seats for free subsequent rotation.
Resilient seals are provided in association with the longitudinal ribs and stops. The seal is maintained during shifting of the diverter element along its axis.